Heat exchange device and heat source machine

ABSTRACT

The heat exchange device includes a primary heat exchanger and a secondary heat exchanger. The secondary heat exchanger is disposed to overlap the primary heat exchanger in a vertical direction in a state in which the heat exchange device is installed. The secondary heat exchanger includes a plurality of first pipes and a plurality of second pipes. Each of the plurality of first pipes and the plurality of second pipes extends in a zigzag manner in the vertical direction by a plurality of linear portions being connected to a plurality of curved portions in series. Each of the plurality of linear portions of each of the plurality of second pipes is disposed to be displaced from each of the plurality of linear portions of each of the plurality of first pipes in the vertical direction.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims the priority benefit of Japan application serial no. 2017-248716, filed on Dec. 26, 2017. The entirety of the above-mentioned patent application is hereby incorporated by reference herein and made a part of this specification.

BACKGROUND Technical Field

The disclosure relates to a heat exchange device and a heat source machine, and more particularly to a heat exchange device having a primary heat exchanger and a secondary heat exchanger and a heat source machine having the same.

Description of Related Art

Conventionally, a heat exchange device including a primary heat exchanger for recovering sensible heat and a secondary heat exchanger for recovering latent heat has been proposed. This heat exchange device is described in, for example, Japanese Laid-open No. 2017-211173 (Patent Document 1). In the heat exchange device described in this publication, the secondary heat exchanger has a plurality of heat absorbing pipes. The plurality of heat absorbing pipes are arranged vertically. Each of the plurality of heat absorbing pipes extends in a zigzag manner in a forward and backward direction.

In the heat exchange device described in the above publication, since each of the plurality of heat absorbing pipes extends in a zigzag manner in the forward and backward direction (horizontal direction), drainage performance is poor when water is discharged from the heat absorbing pipes. Further, since a combustion gas flowing from the primary heat exchanger into the secondary heat exchanger first comes into contact with the uppermost heat absorbing pipe among the plurality of heat absorbing pipes, the uppermost heat absorbing pipe reaches the highest temperature. Therefore, scale (boiler scale) precipitated due to minerals contained in water tends to accumulate in the uppermost heat absorbing pipes more than in the heat absorbing pipes located below the uppermost heat absorbing pipe. As a result, a balance in distribution of water between the plurality of heat absorbing pipes deteriorates.

SUMMARY

A heat exchange device of an embodiment of the disclosure is a heat exchange device which is capable of recovering sensible heat and latent heat of a combustion gas. The heat exchange device includes a primary heat exchanger and a secondary heat exchanger. The primary heat exchanger is for recovering the sensible heat of the combustion gas. The secondary heat exchanger is disposed to overlap the primary heat exchanger in a vertical direction in a state in which the heat exchange device is installed and is for recovering the latent heat of the combustion gas. The secondary heat exchanger includes a plurality of first pipes, and a plurality of second pipes each alternately adjacent to each of the plurality of first pipes in a direction intersecting the vertical direction. Each of the plurality of first pipes and the plurality of second pipes has a plurality of linear portions and a plurality of curved portions connecting the plurality of linear portions with each other and extends in a zigzag manner in the vertical direction by the plurality of linear portions being connected to the plurality of curved portions in series. Each of the plurality of linear portions of each of the plurality of second pipes is disposed to be displaced from one of the plurality of linear portions of one of the plurality of first pipes in the vertical direction.

A heat source machine of an embodiment of the disclosure includes the above-described heat exchange device, and a burner. The burner is disposed on a side of the primary heat exchanger opposite to the secondary heat exchanger. The burner is formed to be able to supply the combustion gas in the order of the primary heat exchanger and the secondary heat exchanger.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 a diagram schematically showing a configuration of a heat source machine according to an embodiment of the disclosure.

FIG. 2 is a perspective view schematically showing a configuration of a heat exchange device according to the embodiment of the disclosure.

FIG. 3 is a side view showing an internal structure of the heat exchange device according to the embodiment of the disclosure with a broken line.

FIG. 4 is a perspective view schematically showing a configuration of a secondary heat exchanger according to the embodiment of the disclosure.

FIG. 5 is an exploded perspective view schematically showing the configuration of the secondary heat exchanger according to the embodiment of the disclosure.

FIG. 6 is a top view schematically showing the configuration of the secondary heat exchanger according to the embodiment of the disclosure.

FIG. 7 is a rear view showing the internal structure of the heat exchange device according to an embodiment of the disclosure with a broken line.

FIG. 8 is a cross-sectional view taken along line VIII-VIII of FIG. 2.

FIG. 9 is a cross-sectional view taken along line IX-IX of FIG. 2.

DESCRIPTION OF THE EMBODIMENTS

The embodiments of the disclosure provide a heat exchange device capable of improving drainage performance and improving the balance of distribution of water and a heat source machine including the same.

A heat exchange device of an embodiment of the disclosure is a heat exchange device which is capable of recovering sensible heat and latent heat of a combustion gas. The heat exchange device includes a primary heat exchanger and a secondary heat exchanger. The primary heat exchanger is for recovering the sensible heat of the combustion gas. The secondary heat exchanger is disposed to overlap the primary heat exchanger in a vertical direction in a state in which the heat exchange device is installed and is for recovering the latent heat of the combustion gas. The secondary heat exchanger includes a plurality of first pipes, and a plurality of second pipes each alternately adjacent to each of the plurality of first pipes in a direction intersecting the vertical direction. Each of the plurality of first pipes and the plurality of second pipes has a plurality of linear portions and a plurality of curved portions connecting the plurality of linear portions with each other and extends in a zigzag manner in the vertical direction by the plurality of linear portions being connected to the plurality of curved portions in series. Each of the plurality of linear portions of each of the plurality of second pipes is disposed to be displaced from one of the plurality of linear portions of one of the plurality of first pipes in the vertical direction.

According to the heat exchanger of one or some exemplary embodiments of the disclosure, each of the plurality of first pipes and the plurality of second pipes extends in the zigzag manner in the vertical direction by the plurality of linear portions being connected to the plurality of curved portions in series. Therefore, when water is discharged from each of the plurality of first pipes and the plurality of second pipes, the water drains from an upper side to a lower side due to gravity, and thus drainage performance can be improved. Further, since the secondary heat exchanger is disposed to overlap the primary heat exchanger in the vertical direction in the state in which the heat exchange device is installed, the combustion gas flows into the secondary heat exchanger in the vertical direction. Since the plurality of first pipes and the plurality of second pipes are disposed in a direction intersecting the vertical direction, each of the plurality of first pipes and each of the plurality of second pipes comes into contact with the combustion gas uniformly. Therefore, scale (boiler scale) is deposited uniformly in each of the plurality of first pipes and each of the plurality of second pipes. Therefore, it is possible to prevent a balance in distribution of the water from deteriorating in each of the plurality of first pipes and the plurality of second pipes. That is, the balance in distribution of the water can be improved. Further, each of the plurality of linear portions of each of the plurality of second pipes is disposed to be displaced from each of the plurality of linear portions of each of the plurality of first pipes in the vertical direction. Therefore, it is possible to reduce flow path resistance when the combustion gas flows in the vertical direction between each of the plurality of linear portions of each of the plurality of first pipes and each of the plurality of linear portions of each of the plurality of second pipes.

In the above-described heat exchanger, the primary heat exchanger includes a plurality of fin pipes. Each of the plurality of fin pipes extends in a direction in which the plurality of linear portions extend. Therefore, the combustion gas flows between each of the plurality of first pipes and each of the plurality of second pipes along a flow of combustion gas flowing between the plurality of fin pipes. Thus, it is possible to reduce the flow path resistance when the combustion gas flows from the primary heat exchanger to the secondary heat exchanger in the vertical direction.

In the above-described heat exchanger, the secondary heat exchanger comprises a circumferential wall portion surrounding the plurality of first pipes and the plurality of second pipes. The circumferential wall portion comprises a main body portion and an expanded portion which expands outward from the main body portion. Each of the plurality of first pipes and each of the plurality of second pipes are disposed in an inner space of the circumferential wall portion surrounded by the main body portion and an inner space of the circumferential wall portion expanded due to the expanded portion. Therefore, the main body portion can be made smaller than the expanded portion. In addition, since the plurality of first pipes and the plurality of second pipes are disposed in the inner space of the circumferential wall portion expanded due to the expanded portion, a heat transfer area of the plurality of first pipes and the plurality of second pipes can be increased as compared with a case in which the expanded portion is not provided. Thus, it is possible to improve heat exchange efficiency of the plurality of first pipes and the plurality of second pipes while the main body portion is miniaturized.

A heat source machine of an embodiment of the disclosure includes the above-described heat exchange device, and a burner. The burner is disposed on a side of the primary heat exchanger opposite to the secondary heat exchanger. The burner is formed to be able to supply the combustion gas in the order of the primary heat exchanger and the secondary heat exchanger. According to the heat source machine according to one or some exemplary embodiments of the disclosure, it is possible to provide a heat source machine including a heat exchange device capable of improving the drainage performance and improving the balance in distribution of the water.

As described above, according to the embodiments of the disclosure, it is possible to provide a heat exchange device capable of improving drainage performance and improving a balance in distribution of water and a heat source machine including the same.

Hereinafter, embodiments of the disclosure will be described below with reference to the drawings.

First, referring to FIG. 1, a configuration of a heat source machine 100 according to an embodiment of the disclosure will be described.

As shown in FIG. 1, the heat source machine 100 according to the embodiment mainly includes a spark plug 1, a primary heat exchanger (sensible heat recovery heat exchanger) 10, a secondary heat exchanger (latent heat recovery heat exchanger) 20, a burner 30, a chamber 31, a blowing device 32, a duct 33, a venturi 34, an orifice 35, a gas valve 36, a pipe 40, a bypass pipe 41, a three-way valve 42, and a housing 50. The primary heat exchanger 10 and the secondary heat exchanger 20 form a heat exchange device 200. All of the above components except for the housing 50 are disposed inside the housing 50. The above-mentioned components are the same as those in the related art except for the heat exchange device 200.

A fuel gas flows to the venturi 34 through the gas valve 36 and the orifice 35. A mixed gas mixed by the venturi 34 is delivered to the blowing device 32. The blowing device 32 is for supplying the mixed gas to the burner 30. The blowing device 32 is connected to the chamber 31, and the chamber 31 is connected to the burner 30. The mixed gas supplied from the blowing device 32 is delivered to the burner 30 through the chamber 31. The burner 30 is for generating a heating gas (combustion gas) which is supplied to the primary heat exchanger 10. The mixed gas blown out from the burner 30 is ignited by the spark plug 1 and becomes a combustion gas.

The burner 30, the primary heat exchanger 10, and the secondary heat exchanger 20 are connected so that a combustion gas sequentially passes through the primary heat exchanger 10 and the secondary heat exchanger 20 to exchange heat with hot water. The burner 30 is disposed on a side of the primary heat exchanger 10 opposite to the secondary heat exchanger 20. The burner 30 is configured to be able to supply the combustion gas in the order of the primary heat exchanger 10 and the secondary heat exchanger 20. In the embodiment, the burner 30 is disposed above the primary heat exchanger 10. In other words, the burner 30 is of a reverse combustion type. Further, the burner 30 may be a premix burner of which a capacity fluctuates over an entire region of a combustion chamber frontage. The duct 33 is connected to the secondary heat exchanger 20, and the duct 33 extends to the outside of the housing 50. Accordingly, the combustion gas which has passed through the secondary heat exchanger 20 is discharged outside of the housing 50 through the duct 33. A portion of the pipe 40 on a hot water outlet side from the primary heat exchanger 10 and the bypass pipe 41 are connected by the three-way valve 42.

Next, a configuration of the heat exchange device 200 of the embodiment will be described with reference to FIGS. 2 to 9. As shown in FIGS. 2 and 3, the heat exchange device 200 is capable of recovering sensible heat and latent heat of the combustion gas. The heat exchange device 200 has the primary heat exchanger 10 and the secondary heat exchanger 20. The primary heat exchanger 10 is for recovering the sensible heat of the combustion gas. The secondary heat exchanger 20 is for recovering the latent heat of the combustion gas. The primary heat exchanger 10 and the secondary heat exchanger 20 are disposed to overlap in a first direction D1. The secondary heat exchanger 20 is disposed to overlap the primary heat exchanger 10 in a vertical direction in a state in which the heat exchange device 200 is installed. That is, in the state in which the heat exchange device 200 is installed, the first direction D1 is the vertical direction.

The primary heat exchanger 10 is connected to the secondary heat exchanger 20. The combustion gas is supplied through an upper opening of the primary heat exchanger 10, and the combustion gas is exhausted through a lower opening of the secondary heat exchanger 20. The hot water entering the secondary heat exchanger 20 from a water inlet portion 20 a of the secondary heat exchanger 20 exchanges heat with the combustion gas, then exits from a hot water outlet portion 20 b and enters a water inlet portion 10 a of the primary heat exchanger 10 via a pipe (not shown). The hot water which has entered the water inlet portion 10 a of the primary heat exchanger 10 exchanges heat with the combustion gas and then exits from a hot water outlet portion 10 b. The water inlet portion 10 a is a portion through which the hot water first enters the primary heat exchanger 10. The hot water outlet portion 10 b is a portion through which the hot water finally exits from the primary heat exchanger 10.

The primary heat exchanger 10 includes the water inlet portion 10 a, the hot water outlet portion 10 b, a heat exchanging portion 11, a shell plate 12, a shell pipe portion 13, a header member 14, and a bend pipe 15. The heat exchanging portion 11 includes a plurality of fins 11 a and a plurality of fin pipes 11 b. Each of the plurality of fins 11 a and the plurality of fin pipes 11 b may be formed of SUS (stainless steel). The heat exchanging portion 11 is configured so that the combustion gas flows outside the plurality of fins 11 a and the plurality of fin pipes 11 b and water flows inside the plurality of fin pipes 11 b. The plurality of fins 11 a are stacked on each other. The plurality of fin pipes 11 b pass through the plurality of fins 11 a. In FIGS. 2 and 3, for convenience of description, only some of the plurality of fins 11 a are illustrated.

The shell plate 12 surrounds the heat exchanging portion 11. The shell plate 12 includes a front surface portion 12 a, a pair of side surface portions 12 b, and a back surface portion 12 c. The front surface portion 12 a, the pair of side surface portions 12 b, and the back surface portion 12 c form a square frame. The shell plate 12 has openings at the top and bottom. The shell plate 12 can supply the combustion gas to the inside of the shell plate 12 through the upper opening. The shell plate 12 can exhaust the combustion gas to the outside of the shell plate 12 through the lower opening.

The shell pipe portion 13 is disposed along inner surfaces of the pair of side surface portions 12 b and the back surface portion 12 c of the shell plate 12. The shell pipe portion 13 includes a first cooling pipe 131, a second cooling pipe 132, and a third cooling pipe 133. The first cooling pipe 131, the second cooling pipe 132 and the third cooling pipe 133 are installed side by side in the first direction D1. The first cooling pipe 131, the second cooling pipe 132 and the third cooling pipe 133 are connected in series via the header member 14. The header member 14 is installed on the front surface portion 12 a of the shell plate 12. The header member 14 includes a first header member 141 and a second header member 142.

One end of the first cooling pipe 131 is connected to the water inlet portion 10 a, and the other end of the first cooling pipe 131 is connected to the first header member 141. One end of the second cooling pipe 132 is connected to the first header member 141, and the other end of the second cooling pipe 132 is connected to the second header member 142. One end of the third cooling pipe 133 is connected to the second header member 142 and the other end of the third cooling pipe 133 is connected to the bend pipe 15 disposed on the uppermost side. The plurality of fin pipes 11 b are connected to each other in series by the bend pipe 15.

As shown in FIGS. 3 and 4, the secondary heat exchanger 20 includes the water inlet portion 20 a, the hot water outlet portion 20 b, a heat exchanging portion 21, a shell plate (circumferential wall portion) 22, and a header member 23. The heat exchanging portion 21 includes a plurality of first pipes 21 a and a plurality of second pipes 21 b. Each of the plurality of first pipes 21 a and the plurality of second pipes 21 b may be formed of SUS (stainless steel). The heat exchanging portion 21 is formed so that the combustion gas flows outside each of the plurality of first pipes 21 a and the plurality of second pipes 21 b and the water flows inside the plurality of first pipes 21 a and the plurality of second pipes 21 b.

Each of the plurality of first pipes 21 a and the plurality of second pipes 21 b is a meandering pipe (meander). The plurality of first pipes 21 a and the plurality of second pipes 21 b are alternately folded back in a second direction D2 orthogonal to the first direction D1. Each of the plurality of first pipes 21 a and the plurality of second pipes 21 b is formed so that the second direction D2 is a longitudinal direction. The plurality of first pipes 21 a and the plurality of second pipes 21 b are stacked on each other in a third direction D3 orthogonal to both the first direction D1 and the second direction D2.

As shown in FIGS. 4 and 5, the shell plate 22 surrounds the plurality of first pipes 21 a and the plurality of second pipes 21 b. The shell plate 22 includes a front surface portion 22 a, a pair of side surface portions 22 b, and a back surface portion 22 c. The front surface portion 22 a, the pair of side surface portions 22 b, and the back surface portion 22 c form a square frame. The shell plate 22 has openings at the top and bottom. The shell plate 22 can supply the combustion gas to the inside of the shell plate 22 through the upper opening. The shell plate 22 allows the combustion gas to be exhausted outside of the shell plate 22 through the lower opening. The shell plate 22 includes a main body portion 221 and an expanded portion 222. The expanded portion 222 expands outward from the main body portion 221. The expanded portion 222 is provided on the front surface portion 22 a. The expanded portion 222 expands from the main body portion 221 toward a side opposite to the back surface portion 22 c.

The header member 23 includes a first header member 231 and a second header member 232. The first header member 231 and the second header member 232 are disposed side by side in the first direction D1. The first header member 231 is disposed farther from the primary heat exchanger 10 than the second header member 232 is. The first header member 231 and the second header member 232 are disposed at both ends of the shell plate 22 in the second direction D2. Each of the first header member 231 and the second header member 232 is configured to extend in the third direction D3. The water inlet portion 20 a is connected to the first header member 231. The hot water outlet portion 20 b is connected to the second header member 232.

As shown in FIG. 5, each of the plurality of first pipes 21 a and the plurality of second pipes 21 b has a plurality of linear portions 21 c and a plurality of curved portions 21 d. Each of the plurality of linear portions 21 c extends in the second direction D2. Each of the plurality of curved portions 21 d extends in the third direction D3. The plurality of curved portions 21 d connects the plurality of linear portions 21 c to each other. Each of the plurality of first pipes 21 a and the plurality of second pipes 21 b extends in a zigzag manner in the vertical direction (first direction D1) by the plurality of linear portions 21 c being connected to the plurality of curved portions 21 d in series. Each of the plurality of first pipes 21 a and each of the plurality of second pipes 21 b are disposed not to overlap each other in the vertical direction (the first direction DD. Each of the plurality of first pipes 21 a and the plurality of second pipes 21 b may have the same shape.

As shown in FIGS. 5 and 6, one end of each of the plurality of first pipes 21 a and the plurality of second pipes 21 b is connected to the first header member 231, and the other end of each of the plurality of first pipes 21 a and the plurality of second pipes 21 b is connected to the second header member 232. The plurality of first pipes 21 a and the plurality of second pipes 21 b are connected in parallel via the first header member 231 and the second header member 232.

As shown in FIGS. 6 and 7, in a state in which the heat exchange device 200 is installed, each of the plurality of first pipes 21 a and the plurality of second pipes 21 b are arranged in a direction (the third direction D3) orthogonal to the vertical direction (the first direction DD. That is, in the state in which the heat exchange device 200 is installed, the third direction D3 is a horizontal direction. The plurality of first pipes 21 a and the plurality of second pipes 21 b are alternately disposed in parallel in the third direction D3. In the state in which the heat exchange device 200 is installed, the plurality of second pipes 21 b alternately adjoin the plurality of first pipes 21 a in a direction (the third direction D3) intersecting the vertical direction (the first direction DD. Each of the plurality of first pipes 21 a and each of the plurality of second pipes 21 b may be alternately brought into contact with each other in the third direction D3.

Each of the plurality of first pipes 21 a and each of the plurality of second pipes 21 b uniformly comes into contact with the combustion gas indicated by a hollow arrow in FIG. 7. Therefore, it is minimized that scale (boiler scale) precipitated due to minerals contained in water is locally deposited in each of the plurality of first pipes 21 a and each of the plurality of second pipes 21 b. Accordingly, a drift of water flowing through each of the plurality of first pipes 21 a and each of the plurality of second pipes 21 b is minimized.

Each of the plurality of first pipes 21 a and each of the plurality of second pipes 21 b are disposed to be displaced from each other in the first direction D1. Each of the plurality of first pipes 21 a is disposed closer to the primary heat exchanger 10 in the first direction D1 than each of the plurality of second pipes 21 b. Each of the plurality of first pipes 21 a comes into contact with the combustion gas indicated by a hollow arrow in FIG. 7 before each of the plurality of second pipes 21 b.

As shown in FIG. 8, each of the plurality of first pipes 21 a and the plurality of second pipes 21 b is disposed in an inner space of the shell plate 22 surrounded by the main body portion 221 and in an inner space of the shell plate 22 expanded due to the expanded portion 222. Specifically, the plurality of curved portions 21 d of each of the plurality of first pipes 21 a and the plurality of second pipes 21 b are disposed inside the expanded portion 222. The plurality of curved portions 21 d of each of the plurality of first pipes 21 a and the plurality of second pipes 21 b are disposed with a gap between an inner surface of the expanded portion 222 and the curved portions 21 d. The expanded portion 222 is disposed between the first header member 231 and the second header member 232 in the first direction D1.

As shown in FIGS. 8 and 9, each of the plurality of second pipes 21 b is disposed farther from the primary heat exchanger 10 in the first direction D1 than each of the plurality of first pipes 21 a. In the state in which the heat exchange device 200 is installed, each of the plurality of linear portions 21 c of each of the plurality of second pipes 21 b is disposed to be displaced from each of the plurality of linear portions 21 c of each of the plurality of first pipes 21 a in the vertical direction (the first direction DD. In the plurality of first pipes 21 a, one linear portion 21 c among the plurality of linear portions 21 c in each of the plurality of second pipes 21 b is disposed adjacent to a region sandwiched between the linear portions 21 c adjacent to each other in the vertical direction (the first direction D1) among the plurality of linear portions 21 c in an intersecting direction (the third direction D3) intersecting with the vertical direction (the first direction D1).

In the embodiment, each of the plurality of linear portions 21 c of each of the plurality of second pipes 21 b is disposed between the plurality of linear portions 21 c of each of the plurality of first pipes 21 a in the vertical direction (the first direction DD. That is, each of the plurality of linear portions 21 c adjacent to each other in the intersecting direction (the third direction D3) intersecting the vertical direction (the first direction D) of each of the plurality of first pipes 21 a and the plurality of second pipes 21 b are disposed not to overlap each other in the vertical direction (the first direction DD. Also, each of the plurality of fin pipes 11 b extends in the second direction D2. Each of the plurality of fin pipes 11 b extends in a direction (the second direction D2) in which the plurality of linear portions 21 c extend.

Next, the operation and effects of the embodiment will be described.

As shown in FIG. 8, according to the heat exchange device 200 of the embodiment, each of the plurality of first pipes 21 a and the plurality of second pipes 21 b extends in a zigzag manner in the vertical direction (the first direction D1) by the plurality of linear portions 21 c being connected to the plurality of curved portions 21 d in series. Therefore, when water is discharged from each of the plurality of first pipes 21 a and the plurality of second pipes 21 b, the water drains from an upper side to a lower side due to gravity, and thus drainage performance can be improved.

Further, as shown in FIG. 9, in the state in which the heat exchange device 200 is installed, since the secondary heat exchanger 20 is disposed to overlap the primary heat exchanger 10 in the vertical direction (the first direction D1), the combustion gas indicated by a solid arrow A in FIG. 9 flows into the secondary heat exchanger 20 in the vertical direction (the first direction DD. Since the plurality of first pipes 21 a and the plurality of second pipes 21 b are disposed in the direction (the third direction D3) intersecting the vertical direction (the first direction D1), each of the plurality of first pipes 21 a and each of the plurality of second pipes 21 b comes into contact with the combustion gas uniformly. Therefore, the scale is deposited uniformly in each of the plurality of first pipes 21 a and each of the plurality of second pipes 21 b. Thus, it is possible to prevent a balance in distribution of the water from deteriorating in each of the plurality of first pipes 21 a and the plurality of second pipes 21 b. That is, the balance in distribution of the water can be improved. Therefore, failure of the heat exchange device 200 can be minimized.

Further, each of the plurality of linear portions 21 c of each of the plurality of second pipes 21 b is disposed to be displaced from each of the plurality of linear portions 21 c of each of the plurality of first pipes 21 a in the vertical direction (the first direction D1). Therefore, it is possible to reduce flow path resistance when the combustion gas flows in the vertical direction (the first direction D) between each of the plurality of linear portions 21 c of each of the plurality of first pipes 21 a and each of the plurality of linear portions 21 c of each of the plurality of second pipes 21 b. Accordingly, a capacity of the blowing device 32 can be reduced, and thus a power consumption and a size of the blowing device 32 can be reduced.

Further, each of the plurality of linear portions 21 c of each of the plurality of second pipes 21 b is disposed between the plurality of linear portions 21 c of each of the plurality of first pipes 21 a in the vertical direction (the first direction DD. Therefore, even if each of the plurality of first pipes 21 a and each of the plurality of second pipes 21 b are in contact with each other in the third direction D3, the combustion gas is caused to flow between each of the plurality of linear portions 21 c of each of the plurality of first pipes 21 a and each of the plurality of linear portions 21 c of each of the plurality of second pipes 21 b in the vertical direction (the first direction D1).

As shown in FIG. 8, in the heat exchange device 200 of the embodiment, each of the plurality of fin pipes 11 b extends in a direction (the second direction D2) in which the plurality of linear portions 21 c extend. Therefore, the combustion gas flows between each of the plurality of first pipes 21 a and each of the plurality of second pipes 21 b along the flow of the combustion gas flowing between the plurality of fin pipes 11 b. Thus, it is possible to reduce the flow path resistance when the combustion gas flows from the primary heat exchanger 10 to the secondary heat exchanger 20 in the vertical direction (the first direction D1).

As shown in FIG. 8, in the heat exchange device 200 of the embodiment, the plurality of first pipes 21 a and the plurality of second pipes 21 b are disposed in the inner space of the shell plate 22 surrounded by the main body portion 221 and the inner space of the shell plate 22 expanded due to the expanded portion 222. Therefore, the main body portion 221 can be made smaller than the expanded portion 222. Also, since the plurality of first pipes 21 a and the plurality of second pipes 21 b are disposed in the inner space of the shell plate 22 expanded due to the expanded portion 222, a heat transfer area of the plurality of first pipes 21 a and the plurality of second pipes 21 b can be increased as compared with a case in which the expanded portion 222 is not provided. In the expanded portion 222, since heat exchange is performed between the combustion gas indicated by a solid arrow A in FIG. 8 and the plurality of first pipes 21 a and the plurality of second pipes 21 b, it is possible to improve a heat exchange amount. Therefore, it is possible to improve heat exchange efficiency of the plurality of first pipes 21 a and the plurality of second pipes 21 b while the main body portion 221 is miniaturized.

As shown in FIG. 1, the heat source machine 100 of the embodiment includes the above-described heat exchange device 200 and the burner 30. The burner 30 is formed to be able to supply the combustion gas in the order of the primary heat exchanger 10 and the secondary heat exchanger 20. According to the heat source machine 100 of the embodiment, it is possible to provide the heat source machine 100 including the heat exchange device 200 capable of improving the drainage performance and improving the balance in distribution of the water.

It will be apparent to those skilled in the art that various modifications and variations can be made to the disclosed embodiments without departing from the scope or spirit of the disclosure. In view of the foregoing, it is intended that the disclosure covers modifications and variations provided that they fall within the scope of the following claims and their equivalents. 

What is claimed is:
 1. A heat exchange device which is capable of recovering sensible heat and latent heat of a combustion gas, comprising: a primary heat exchanger which recovers the sensible heat of the combustion gas; and a secondary heat exchanger which is disposed to overlap the primary heat exchanger in a vertical direction in a state in which the heat exchange device is installed and which recovers the latent heat of the combustion gas, wherein the secondary heat exchanger comprises a plurality of first pipes, and a plurality of second pipes each alternately adjacent to each of the plurality of first pipes in a direction intersecting the vertical direction, each of the plurality of first pipes and the plurality of second pipes has a plurality of linear portions and a plurality of curved portions connecting the plurality of linear portions with each other and extends in a zigzag manner in the vertical direction by the plurality of linear portions being connected to the plurality of curved portions in series, and each of the plurality of linear portions of each of the plurality of second pipes is disposed to be displaced from each of the plurality of linear portions of each of the plurality of first pipes in the vertical direction.
 2. The heat exchange device according to claim 1, wherein the primary heat exchanger comprises a plurality of fin pipes, and each of the plurality of fin pipes extends in a direction in which the plurality of linear portions extend.
 3. The heat exchange device according to claim 1, wherein the secondary heat exchanger comprises a circumferential wall portion surrounding the plurality of first pipes and the plurality of second pipes, the circumferential wall portion comprises a main body portion and an expanded portion which expands outward from the main body portion, and each of the plurality of first pipes and each of the plurality of second pipes are disposed in an inner space of the circumferential wall portion surrounded by the main body portion and an inner space of the circumferential wall portion expanded due to the expanded portion.
 4. A heat source machine, comprising: the heat exchange device according to claim 1; and a burner disposed on a side of the primary heat exchanger opposite to the secondary heat exchanger, wherein the burner is formed to be able to supply the combustion gas in the order of the primary heat exchanger and the secondary heat exchanger. 